Digital Coast

Sail at Low Tide?

Submitted by Keil Schmid on January 18, 2012

The tide is high out
on the bay

I guess we should hold out
on this day

Lidar collection is gonna have to wait
The shoreline has to be straight

What marshes look like can be worse
Much will be lost of course

Models and imagery makes it clear
It’s best to wait till tidal flats appear

Hydro-enforcing different water elevations
will leave you with some lingering reservations


What's the Scenario?

Submitted by Doug Marcy on January 4, 2012

At some point in the climate adaptation planning process you might have to choose a sea level rise scenario(s).  One(s) that incorporate global projections and local change rates. Most plans use a span of 100 years or time horizon of 2100 as the endpoint.


The Ocean Is Not Flat

Submitted by Doug Marcy on December 12, 2011

Just as the surface of the Earth is not flat, the surface of the ocean is not flat. For instance, the absolute water level height is higher along the West Coast of the United States than the East Coast. The surface of the sea changes at different rates around the globe.


Lies, Damned Lies, and Accuracy Assessment

Submitted by Nate Herold on December 5, 2011

“There are three kinds of lies: lies, damned lies, and statistics.”  Mark Twain popularized this saying, describing the persuasive power of numbers (particularly to bolster a weak argument).  Accuracy Assessments can often be thought of in the same light.  All too often these numbers are accepted at face value, without question. 


The only thing constant is change.

Submitted by John McCombs on November 28, 2011

 

What is a Change Matrix? No, it’s not something from the movie involving Neo or computers using humans as their energy source.  Although at first glance it can be just as confusing.  A change matrix is a table, similar to a spreadsheet that quantifies the amount of change that occurs between two dates of land cover.  It can be used to analyze the multitude of potential land cover change...


Spatial Detail VS. Map Accuracy (and the concept of spatial rounding)

Submitted by Nate Herold on November 21, 2011

I wrote a few weeks ago about resolution and stressed the equally important (and often under appreciated) concept of Minimum Mapping Unit (MMU).   And, that if you have a significantly large MMU, it almost doesn’t matter what the input resolution of the imagery was.  I’m going to build on that previous discussion a bit and make a slightly finer distinction between level of spatial detail (represented by those two previously covered concepts) and mapping accuracy. 


You say "to-may-to", I say "to-mah-to"

Submitted by John McCombs on November 14, 2011

What is the difference between land cover and land use?


OMGeoid

Submitted by Kirk Waters on November 7, 2011

Every so often I get a question from someone that makes me realize I haven’t done a good enough job of describing what’s going on in the lidar distribution system of Digital Coast and why we do certain things that might appear crazy.  The most recent one involved a data set that is about five years old and a user was trying to fill some gaps in their copies of the original data.  When they downloaded the data from Digital Coast, they were showing just over half a foot vertical difference from the originals, though the points were horizontally right on.


Resolution Vs. Minimum Mapping Unit: Size Does Matter

Submitted by Nate Herold on October 28, 2011

As a producer of moderate resolution land cover data, I am often asked questions about the spatial resolution of our data.  I have gotten used to the fact that 30 meter pixels of our C-CAP data are not always seen as ultra-sexy and the reaction that they “are not good enough.”  And they aren’t in some instances, but then again, sometimes they are (and sometimes it doesn’t matter, as they are the only/best thing available).  What I tell people, though, is that the resolution itself isn’t enough to determine whether these p


Accuracy standards for sea level rise mapping

Submitted by Kirk Waters on October 24, 2011

Over the last year we’ve been working on mapping the possible inundation that sea level rise would bring to the coastal community. We quickly ran into a serious question. What amount of rise can we map given the accuracy of the elevation? This ought to be an easy question. Surely there are mapping standards we could follow. Alas, there are multiple mapping standards and what you pick depends on what you think you’re doing and the assumptions you make about that process. I’m going to look at a few options for looking at the problem and maybe a different way to think about mapping standards.


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